This invention relates to an improved particulate material cleaning and storing apparatus and to a reproducing apparatus employing it. The cleaning apparatus is adapted to clean residual toner material, etc., from the surface of a reusable image retaining surface.
A wide variety of toner cleaning and storage systems have been devised in the prior art. In U.S. Pat. Nos. 3,740,789 to Ticknor, and 3,742,551 to Oriel, cleaning and storage apparatuses similar in many respects to that employed in the Xerox 3100 copier as described. A blade cleaning device is utilized to separate residual toner from the surface of a xerographic drum. The removed toner is then transported rearwardly into a sump by means of a seal roll and paddle wheel arrangement.
Yet another approach for cleaning and storing toner is described in U.S. Pat. Nos. 3,660,863 to Gerbasi, and 3,724,019 to Shanley. These patents are exemplary of a cleaning system similar in many respects to that employed in the Xerox 4000 copier wherein a blade cleaning means is utilized to remove toner from the surface of a xerographic drum. The removed toner is then transported by means of an auger to a conveying device whereby it is recirculated to the development system for reapplication to the xerographic surface.
The cleaning and storage apparatuses described in U.S. Pat. Nos. 3,740,789 and 3,742,551, employing non-recirculating sumps are particularly adapted for use in a compact reproducing machine such as the Xerox 3100 copier. The sumps described in these patents have a limited capacity and, therefore, periodically must be cleaned out. It has been found, however, that the period required between cleanings of the sump can be severely shortened depending on the mode in which the machine is operated and the configuration of the sump itself.
For example, when copying a document which does not cover the entire platen surface, and the platen is otherwise left uncovered, dense solid areas on one or both ends of the xerographic drum, depending on whether corner or center registration is employed respectively, develop out on the drum. This causes the sump to fill up unevenly. This problem can be further compounded by having a sump of uneven volume.
In the 3100 copier corner registration is employed so that such solid areas develop on the in-board end of the drum which in turn causes the in-board end of the cleaner sump to fill up before the out-board end. As will be described in greater detail hereafter, the sump configuration utilized provides a smaller sump volume on the in-board end in order to accommodate other elements of the machine. As a result the in-board side of the cleaner sump tends to overflow into the remaining machine environment after a given interval while the out-board side of the sump may be less than one-third full.
One approach which can partially solve this problem is described in U.S. Pat. No. 3,792,913 to Simmons. This patent describes a xerographic erase mechanism which is adapted to prevent the development out of the dense solid areas on the end of the drum. While this approach is effective to reduce the problem the present invention attacks the problem in a much simpler fashion and is also effective with sumps of uneven volume.